The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.
In a broadcasting service, image media contents can be transmitted for each channel of multi-channels. The inventor(s) has noted that a multi-channel service is to allow users (i.e., users' terminal devices or users' equipments) to watch four-channel images on one channel. The inventor(s) has further noted that a multi-view service is to allow users to selectively watch multi-angle images shot in such sports fields (or arena or stadiums) as, for example, a baseball, a football, and so on, enabling a simultaneous playback of a plurality of images by displaying the plurality of images at a time on a display device of a user terminal device, as is provided by an image sharing. The inventor(s) has noted that although such a service plays back video bit streams received from respective channels separately on the user terminal device, the user terminal device with insufficient resources allocated to receive and play back video images of a plurality of channels typically involves a transmitting terminal to mix and transmit the images of the plurality of channels on one channel (i.e., a single channel).
Further, in case of a video conference call or a video group call, images are received from each participant to layout the images suitably for each participant by using a mixing device in the form of hardware or software. The inventor(s) has noted that the encoded codes of the images are then transcoded (i.e., encoded after decoding) for transmission in the one channel. For example, in case where four users A, B, C and D participate in the video conference call or the video group call, user A receives a single image (e.g., integrated image to show other users B, C and D other than user A) with images of users B, C and D combined except for the user A's own image, while the user B receives a single combined image of users A, C and D except for the user B's own. The inventor(s) has noted that a CCTV control system also receives and combines multiple images captured from a plurality of cameras on a single screen of a display device of the CCTV control system in order to enable the multiple images to be monitored unitarily on the single screen.
Further, in the process of optimizing the bit streams by adjusting the bit rates of the bit streams for multi-channel input images, the images can be encoded or transcoded by setting region of interest (ROI) for the entire image or a specific image. However, the inventor(s) has experienced that the location of the ROI is fixed, which requires the entire image to be transcoded and this is true even with the ROI relocated for the transcoding.
The inventor(s) has experienced that in such a video conference call or video group call, a transcoding is needed to decode the delivered image as having been encoded and then encode it back. Thus, the inventor(s) has experienced that not only the quality of the image is likely to decrease, but the entire coding time is delayed by the transcoding, which causes a delay of the display time.